2026 · Q87
For the next two (02) items that follow:
X is an alloy of copper and zinc. Y is an alloy containing 80% of copper, 4% of zinc and 16% of tin. A fused mass of X and Y is found to contain 74% of copper, 16% of zinc and 10% of tin.
87. What is the percentage of copper in X?
Elementary MathematicsRatio and Proportion
- A60%
- B64%
- C66%
- D70%
Explanation
Only alloy Y contains tin (16%), so the fraction of Y in the mix is 10/16=0.625. For copper: 0.375c+0.625×80=74, giving c=64% copper in X, option B. The tin content is the linchpin: it appears only in Y, fixing the mixing ratio before copper is even considered.